Active stabilization platforms are useful for many applications which require a hand-held device to maintain a steady point of aim such as: camera systems, binoculars, surgical instruments, surveyor's tools, and weapon systems. Hand-held platforms can be greatly improved by an actuated mechanism operating between the point at which the operator holds the device and the aiming point of the device, to cancel relatively high frequency jitter motions induced by the arms and body, but allowing relatively low frequency intentional aiming motions.
One of many applications for a hand-held active stabilization system is small arms (e.g., pistols and rifles) stabilization to improve marksmanship. Good marksmanship is essential for the success of modern infantry forces in combat [a,b]. It is indispensable for effective infantry operations in urban environments, which has been noted as the battlefield in which future U.S. military operations are to occur [c]. Combat in these urban warfare environments place high demands on accurate fire due to the intermingling of civilians and combatants, the close proximity of enemy forces, and the ever varying urban landscape. In such environments, good marksmanship skills significantly improve a soldier's survivability. This was one of the most important lessons learned from a recent urban warfare operation, the battle in Mogadishu, Somalia, in 1993, where well-aimed, accurate fire enabled a small, highly trained U.S. force to hold off thousands of Somali militiamen during urban combat operations [d]. It is important to note that the soldiers who participated in the Somalia operation were elite forces including elements of the Delta Force, Seals and Army 10th Mountain division, and their considerable marksmanship skills significantly exceed those of the average infantry soldier.
The U.S. Army has long recognized the importance of good marksmanship skills as they relate to soldier survivability and has established marksmanship training and qualification programs to teach these skills to the infantry soldier [a,b]. However, attaining and maintaining proficiency in marksmanship is a costly, resource and time consuming process with varying degrees of effectiveness. Even with the extensive training, a significant number of soldiers are not able to attain the Expert, or higher levels of marksmanship qualification. It has also been shown that in actual combat situations, which cannot be effectively simulated in training, this deficiency hampers their ability to perform on the battlefield and thereby limits the combat related tasks they can perform. To address this deficiency there exists a need to improve the shooting performance of these lesser skilled soldiers by methods other than the standard formal marksmanship training, which in these cases has proven to be ineffective.
In combat situations, even for the best trained and talented shooters, it is often difficult to perform the fundamentals inherent in good marksmanship techniques, which include assuming and maintaining a steady position, aiming, controlling breathing and executing a proper trigger squeeze [a,b]. For example, in combat, the terrain and time frame of the immediate circumstances often dictate the choice of shooting position including the availability of steadying supports. Because of this, the shooter does not always have the time or luxury of choosing a steady prone position with sandbag support for the weapon. He or she must react to the situation and assume the most expedient position from which to deliver fire. Often this means employing a position that is not optimal from a steadying standpoint, making it more difficult and time consuming to steady the rifle for fire.
It is estimated by the Army that 90% of the errors contributing to a shooter missing his or her intended target in range qualification can be attributed to aiming errors which include shooter induced disturbances, inaccurate range and wind estimation, and weapon anomalies. In these non combat situations, shooter induced disturbances account for approximately 20% of this error [f]. Further complicating the shooting task is that, when subjected to the stress of combat, the shooting accuracy of all soldiers degrades. According to U.S. Army Small Arms Program personnel, the levels of shooter induced disturbances in combat situations are typically at least an order of magnitude higher than those seen in non-combat situations [e]. This is echoed by U.S. Army Joint Service Small Arms Program (JSSAP) program manager Steve Mango when describing the effects of combat stress on the soldier's performance using the M16. “The M16 is a very accurate weapon. However, when it is placed in the hands of an individual under combat-stress conditions, its performance is reduced dramatically.”[g]
Another area in which the U.S. Army has identified a deficiency in marksmanship at the squad level is the ability to engage targets between the maximum range of the average soldier, 300 meters, and the typical range of trained snipers, 600 meters and beyond [e]. To address this need the U.S. Army has develop the Squad Designated Marksman Program (SDM). The primary mission of the SDM is to deploy as a member of the rifle squad. The SDM is not a squad sniper but fires and maneuvers with his/her squad and performs all of the duties of a rifleman. His/her secondary mission is to engage targets from 300-500 meters with effective, well aimed fires using a standard weapon and ammunition. The SDM may not have an optic sight and therefore, must possess a significant mastery of marksmanship. In order to meet the personnel needs arising from placing an SDM in each squad, a significant number of soldiers highly skilled and trained in marksmanship will be required.
In combat, physiological responses with direct effect on gun aiming performance such as heart beat, respiration, and muscle jerk motion increase significantly and interfere with a soldier's ability to keep the gun aimed on target [h,i]. To attain accurate fire from small arms weapons, such as assault or sniper rifles, the shooter must maintain extremely precise control over the weapon point of aim during the aiming and firing process. For example, to hit a standard military man-sized target silhouette at 300 m, the shooter must control the deviation in the gun angular orientation (both elevation and azimuth angles) to within ±0.83 mrad (±0.09°) of the nominal orientation (rifle aim point at the center of target). Of course, in combat enemy forces are usually concealed and present a much smaller target than the standard silhouette shape; thereby, requiring substantially more precise control of weapon for the round to hit the target. Reducing or eliminating the shooter induced disturbances, especially in combat situations, can have a substantial impact on the accuracy of fire. Despite all the advances in technology over the past century, there have been very few changes introduced into military rifles to address this problem.
Thus, there exists a need for a method and apparatus for stabilizing hand held devices such as small arms and other weapon systems, cameras, binoculars, surgical instruments, surveyor's tools, and the like.